B Finding the distance of two points from observer

[Tahmeed]

Lets suppose that two points A and B are very close together compared to their distance from an observer who is very far. Suppose the distance from observer to point A is DA and to point B is DB. How precisely we can find the distances separately.

 

[BvU]

How precisely we can find the distances separately

Your question isn't clear to me: Aren't the two observations independent ?

 

[Tahmeed]

Your question isn't clear to me: Aren't the two observations independent ?

There can be aberration.

 

[BvU]

Can you illustrate what you mean with a sketch ?

 

[Tahmeed]

Can you illustrate what you mean with a sketch ?

Yes, i will.

 

[russ_watters]

Lets suppose that two points A and B are very close together compared to their distance from an observer who is very far. Suppose the distance from observer to point A is DA and to point B is DB. How precisely we can find the distances separately.

I'm sorry, but as written, the scenario seems like a non-sequitur: There isn't anything described that enables determining distance at all and even if there was, it wouldn't make any difference if the two objects were near to each other or not.

Is this question about Halton Arp?

 

[Tahmeed]

 

[Tahmeed]

how precisely can we measure the DA and DB here?

 

[Drakkith]

Tahmeed, your situation is still unclear. What do points A and B represent? What are the approximate distances you're asking about? The precision and error of our measurements greatly depend on how far away the objects are. Nearby stars are relatively easy to measure, but beyond a few hundred or thousand light years things begin to change since parallax cannot be used. And if you're asking about cosmological distances (greater than a few million light years) then that's a very different scenario indeed...

 

[newjerseyrunner]

Are you trying to simply determine the distance between A and B based on known angle of separation between them and known distances? You can know that exactly using pretty basic geometry.

I would set DB to be your x axis, then use trig to figure out (XA, YA).
The orange vertical is YA.
The orange horizontal is then XA - DB.
The pink line is found using the Pythagorean theorem.

 

[Simon Peach]

if they are a long way away wouldn't you use the small angle approximation?

 

[Tahmeed]

Are you trying to simply determine the distance between A and B based on known angle of separation between them and known distances? You can know that exactly using pretty basic geometry.

View attachment 113274

I would set DB to be your x axis, then use trig to figure out (XA, YA).
The orange vertical is YA.
The orange horizontal is then XA - DB.
The pink line is found using the Pythagorean theorem.

Yes, its kinda like this, but if the error in measurement of DA and DB is higher than their separation, then will we be able to find outt their actual seperation? so i wanted to know how precisely we can measure DA and DB

 

[newjerseyrunner]

No, if you turn those values into variables, then the equation can only be made to provide a range.

Find the values for DB and DA that place them closest together and those that place them furthest apart. That's your range.

 

[Tahmeed]

Are you trying to simply determine the distance between A and B based on known angle of separation between them and known distances? You can know that exactly using pretty basic geometry.

View attachment 113274

I would set DB to be your x axis, then use trig to figure out (XA, YA).
The orange vertical is YA.
The orange horizontal is then XA - DB.
The pink line is found using the Pythagorean theorem.

I got my answer here. thanks